This invention relates to apparatus for use with instant or self-developing type film units, and more particularly to a camera having a lighttight imbibition chamber for storing a film unit until a visible image has been substantially formed therein.
Attempts to decrease the volume of apparatus for use with instant type film, e.g., cameras and camera backs, have been successful, in part, by providing the film units with either a chemical or mechanical opacification system for preventing further exposure of the film unit's emulsion or photosensitive layer by the ambient light during the formation of a visible image, thus obviating the need for a lighttight imbibition chamber in the apparatus. However, providing such apparatus with a lighttight imbibition chamber may provide one with benefits which offset, in part, any disadvantage caused by the space which it takes up. For example, less of the opacification material, e.g., opacifying dyes, would be needed in the processing liquid of an instant type film unit which is to be maintained in a light free environment, subsequent to the spreading of the processing liquid across a layer of the film unit, until the latent image within the film unit is no longer susceptible to being further exposed by ambient light. Thus, the cost of the processing liquid would be less, the layer of processing liquid which is to be spread between the image receiving layer and the photosensitive layer could thereby be thinner thus improving resolution of the image and reducing the time required to produce a visible image.
The overall volume of instant type cameras having lighttight imbibition chambers may be minimized by moving the film unit away from its cassette and then reversing its movement and directing it to an imbibition chamber located substantially under the cassette. Typical examples of such cameras are described in U.S. Pat. Nos. 3,687,032, 3,683,771, and 3,537,370. However, each of these cameras needs an additional housing for temporarily enclosing the film unit during its movement away from the film cassette.
U.S. Pat. No. 3,426,664 discloses yet another type of instant camera in which the imbibition chamber is located rearwardly of a film cassette. In this camera, miniaturization is further enhanced by bending the exposed film unit around a motor prior to moving it toward the imbibition chamber rather than moving the film unit in a reciprocating manner, as described in the aforementioned patents.
A basic fault with the cameras described above is that one must open the camera in order to view an exposed film unit while it is located in the imbibition chamber. In other words, the user of the camera must handle the film unit in order to determine if he has correctly captured on film the scene which he was attempting to photograph. Such handling of the film unit could result in other film units located in the imbibition chamber being inadvertentaly withdrawn and dropped on the ground. Still further, if the user desires to return the film unit to the imbibition chamber for temporary storage, care must be taken to insure its proper placement therein such that it will not interfere with any subsequent film units entering the imbibition chamber.
U.S. Pat. No. 4,265,525 granted to Joseph A. Stella et al. describes an instant type camera which is adapted to receive a film cassette containing a rotatable disc carrying seven film units of the instant type. The film cassette includes a first aperture in a forward wall through which the film units are adapted to be sequentially aligned and exposed, and a second opening located in alignment with a third opening in the cassette's bottom wall. After exposure of a film unit, the disc is rotated so as to move the exposed film unit past a spreader bar which ruptures a pod of processing liquid and spreads its contents across the exposed film unit to initiate the formation of a visible image therein while simultaneously advancing the film unit to a position between and in alignment with the second and third openings. The second and third openings are located in alignment with openings in the camera's top and bottom walls thus enabling the exposed film unit (a positive transparency) to be viewed in place. Should the film units be of a type which require a light free environment during imbibition of the processing liquid, a blind may be provided on the film cassette or on the camera. Apparently, the blind would be located in lighttight relation with the second and third openings until such time that the ambient light would not adversely affect the developing image. Then, the blind would be manually moved to an inoperative position to allow viewing of the visible image within the film unit.
While the camera described in the '525 patent allows for in place viewing of the processed film unit, one must be careful not to move the blind to its inoperative position too early thus possibly fogging the resultant photograph image. Further, the processed film unit cannot be removed from the camera for whatever reason, such as comparison with another photograph or for viewing by others while the photographer is exposing the next film unit, unless the entire film cassette is removed from the camera, thus temporarily stopping further photographic action regarding that film cassette. Still further, if the film cassette were removed from the camera for viewing of the processed film unit, movement of the blind to a position uncovering the second and third openings would result in the first opening also being uncovered, thereby fogging the underlying unexposed film unit.